The term “hollow organs” denotes, for example, blood vessels as well as the structures through which urine flows and the hollow organs of the digestive tract etc., and the need to connect such organs arises very often in surgery. In all such cases a distinction is made between end-to-end anastomoses, in which two ends of two hollow organs are connected to one another, and end-to-side anastomoses, in which the end of one hollow organ is put into communication with a second organ at the side of the latter.
For connecting hollow organs the predominant techniques involve stitching, such that a plurality of sutures create the junction. Apart from the great surgical effort involved here, in particular in the case of small vessels, the region of the sutures is frequently affected by complications such as thromboses, in the case of blood vessels.
In addition to the stitching techniques, there also exist adhesive techniques, for instance employing fibrin adhesives, which allow anastomoses to be formed more rapidly than is the case with sutures, and furthermore the resulting connections are more elastic. It is disadvantageous here that many adhesives are thrombogenic and toxic, and hence are not to be recommended, in particular for vascular anastomoses.
In addition to the above-mentioned stitching and adhesive techniques, clamping techniques are used in which specially shaped clamps create the vessel connections; these can be attached in less time than it takes to stitch conventional sutures. To assist the production of anastomoses, since the beginning of the 20th Century various accessories such as rings, “cuffs” or stents have been used, by means of which secure, rapid and reliable connections can be created. The disadvantage here is that these accessories ordinarily remain in place after the organs have been connected, and then can elicit rejection responses or, in the case of vascular anastomoses, can increase the risk of thromboses. To avoid these problems it has been specified that these accessories be made of materials that disintegrate after a certain time, as described for instance in the document DE 44 17 528 A1. The document EP 0 554 990 B1 describes an apparatus of the kind cited above for constructing anastomoses in which the hollow organs are connected by means of sutures and clamps. The sleeves used to promote anastomosis formation can be made separable, so that they can be removed after anastomosis formation has been completed. Subsequently, however, the sutures and clamps still remain in the hollow organ, where they can increase the risk of thrombosis if the anastomosed structures are vessels.
Laser energy can also be employed to connect biological tissue: when it is applied to hollow organs that are to be connected, the resultant heating causes the tissue of the organs to become fused. Anastomoses thus created by laser exhibit a less pronounced foreign-body reaction. With respect to thrombogenesis, however, no advantage of this approach has yet been demonstrated. Furthermore, the temperatures produced by a laser can also cause destruction of the tissue. An apparatus for fusing biological tissue by means of laser energy is described, for example in the document EP 480 293 A1.
In addition to the production of heat by means of lasers, methods also exist in which local temperature elevations for the purpose of fusing biological tissue are produced by means of electrical current. If the tissue temperature remains below a value of about 100° C., the result is that the substance of the cells coagulates and their protein structures stick to one another in a disorderly manner, so that tissues can become fused. This kind of seamless method of producing vessel anastomosis has been implemented, for example, by means of wire rings disposed around the ends of the vessels, with the supplementary use of fibrin adhesives (E. Wintermantel: The thermic vascular anastomosis (TVA). A new nonsuture method. I. History, Instruments and microsurgical technique; Acta Neurochir. 1981; 56 (1-2): 5-24). The tissue coagulation was produced by imposing several brief current pulses. The wire rings through which the current was introduced, however, were left in place at the anastomosis site. A device for the electrothermal implementation of tissue connections has also been described in the document WO 98/38935 A1.
Another device for the suture-free production of end-to-end anastomoses is described in the document WO 99/63910 A1; here the inserted stent remains in the vessel after anastomosis formation is complete. In this case substantially cylindrical transplants made of metal, plastic or the like are connected by way of likewise cylindrical elements to the ends of the hollow organs or vessels that are to be connected. Connection of the elements to the vessel wall can be brought about, for example, by means of high-frequency current or conventionally, by inserting stitches. This operation always leaves elements in the vessel, which in the case of blood vessels increases the risk of thrombosis. Although this risk can be reduced by applying coatings of heparin or thrombolytic substances, it can never be entirely excluded.